Cortical processing of sensory information is critical for normal perception, memory and most higher order cognitive functions. Disruption of cortical processing is a fundamental cause of disability in many disease and aging disorders. This proposal will develop and apply micro-electrode array technology and novel analytical tools to examine odor information processing in the olfactory (piriform) cortex of rats. The specific aims are to 1) determine whether single-units in piriform cortex entrain to each other and/or with local field potentials during odor stimulation, and 2) whether the magnitude of this entrainment changes with odor experience. These aims are guided by three specific hypotheses: 1) We hypothesize that single-units in piriform cortex will entrain to each other and/or with local field potentials during odor exposure, forming odor-specific cortical ensembles. 2) We hypothesize that single cortical neurons will participate in more than one odor-dependent cortical ensemble. 3) We hypothesize that odor experience and/or associative odor learning will modify cross-correlation's between activity of anterior piriform cortex cell pairs responding to familiar or learned odor compared to novel odors. Multiple single-units and local field potentials will be recorded in anterior piriform cortex of anesthetized rats using micro-electrode arrays fabricated in our lab (Rennaker). Odors will be delivered using flow-dilution olfactometers in stimulation paradigms developed to maximize large datasets (Wilson) necessary for spike train and correlation analyses (Bastian and Rennaker). This proposal brings together three researchers with unique backgrounds to apply techniques not previously utilized in olfactory cortex, yet proven to be extremely powerful for understanding other systems. This combination is ideally suited for the R21 mechanism.